U.S. Pat. No. 4,849,896 discloses a procedure for determining a driver command wherein the position of an operator-controlled element, which is actuated by the driver, is determined by means of a measuring device. In the mentioned embodiment, the operator-controlled element is an accelerator pedal. To trigger, for example, a kickdown operation for the transmission control of the motor vehicle, the wanted shift function is triggered when a pregiven threshold value is exceeded by the detected position of the accelerator pedal.
German patent publication 198 56 963 discloses another application of the kickdown shift signal. In this solution, there is a speed limiter which limits the speed to a limit value selected by the driver. This speed limiting function is disabled when a predetermined position is exceeded by the driver input (for example, the accelerator pedal position), that is, when a kickdown shift signal is generated.
It is common to both solutions that, for detecting or generating the kickdown signal, only the driver pedal position value or a signal representing the latter is evaluated.
Another known solution comprises using a mechanical kickdown switch.
A more precise optimized detection of the kickdown command of the driver is made possible with the utilization of the pedal gradient, that is, the time-dependent trace of the pedal position or a desired value derived therefrom. In this way, the function (switch-off of a drive speed limiter, downshifting of an automatic transmission, et cetera), which is triggered by the kickdown shift signal, is only triggered when a corresponding driver command is reliably detected.
In an advantageous manner, a precise reliable kickdown detection without an additional mechanical kickdown switch is made possible in this way.
It is especially advantageous that the threshold value for the pedal gradient is pregiven as a function of the pedal position or of a desired value derived therefrom. In this way, an adaptation of the kickdown detection is made possible to each driving situation.
It is especially advantageous that the reliability of the kickdown detection is increased by the plausibility of the available signals.